Wetting mechanism for offset printing machines



WETTING MECHANISM FOR OFFSET PRINTING MACHINES Sheet Filed Aug. 28,196'? Inventors Fig.2

TORNEBS March 11, 1969 R. WINKLER .ETAL 3,431,842

WETTING MECHANISM FOR OFFSET PRINTING MACHINES Filed Aug. 28, 1967 Sheet2 of 2 7 Q Fig.3

Inventors R. WL n/der w: Ounneber A TTOVLN 595' United States Patent3,431,842 WETTING MECHANISM FOR OFFSET PRINTING MAQHINES RichardWinkler, Rengsdorf, and Kurt Dunnebier, Gladbach, Germany, assignors toWinkler & Dunnebier Machinenfabrik und Eisengiesserei KG, Neuwied amRhein, Germany, a corporation of Germany Filed Aug. 28, 1967, Ser. No.663,622 Claims priority, application Germany, Dec. 5, 1966,

US. c1.101-142 3 Claims Int. (:1. B41f 9/00; B411 23/00, 25/00 ABSTRACTOF THE DISCLOSURE A wetting mechanism is intended for use with an offsetprinting machine having at least three form rollers and at least twovibrator rolls engaging the form rollers. The wetting mechanism includesa transfer roller engaging a squeezer roller which engages a scooproller mounted in a trough for the wetting liquid. The transfer rolleris in engagement either directly with one of the vibrator rolls or witha rubber roller which engages the vibrator rolls. The scoop roller maybe moved in and out of contact with the transfer roller during theoperation of the printing machine. Additional squeezer rollers may belocated around the scoop roller and a blower may be provided between thesqueezer roller and the transfer roller.

This invention refers to a wetting mechanism for offset printingmachines. More particularly the invention relates to a wetting mechanismwhich applies wetting liquid together with ink, distributed as evenly aspossible over a plurality of form rollers, upon the printing plate of anoffset printing machine, more particularly an offset printing machinehaving three or four form rollers for each inking mechanism and two ormore vibrator rolls running in contact with the form rollers.

German Patent No. 678,543 describes a wetting mechanism in which one ormore rollers of the inking mechanism is in contact with awater-receiving roller to which the necessary quantity of water isdirectly or indirectly fed. It is furthermore known, for example fromGerman Patent No. 1,127,369, to regulate the quantity of the wettingmedium fed to the form cylinder by providing a transfer roller betweenthe wetting roller which dips into the wetting medium storage tank andthe subsequent distributor roller, the transfer roller being mounted soas to oscillate by itself or together with the entire wetting mechanism,bearing on the distributor roller for variable periods for time.

Extensive experiments with inking mechanisms having, for example,fifteen inking rollers following the vibrator have shown that thewetting liquid is imperfectly accepted and unevenly distributed by aninking mechanism roller, the surface of which is still covered with arelatively thick and as yet unevenly distributed coating of ink andwhich is close to the vibrator of the inking mechanism, resulting inreduced printing quality. The quality of printing is substantiallyimproved if the wetting liquid is fed to the vibrator rolls running incontact with the foam rollers from the inking mechanism.

It has been also found that, with periodic supply of wetting liquid atthe last-mentioned location, by means of an oscillatingly mountedtransfer roller, an even wetting of the printing form cannot beachieved. Furthermore, a roller of this type which feeds wetting liquidperiodically requires a particular drive running at the peripheral speedof the printing form, as otherwise the ink is unevenly distributed overthe cover of the inking mechanism roller.

3,431,842 Patented Mar. 11, 1969 It has also been found that theso-called stencil phenomena, which are caused by the fact that thecoating of ink at those parts of the form rollers which have suppliedink to the printing form does not receive the same thickness as at theother places until the next delivery of ink, take place infrequently ifthe wetting liquid is applied to the printing formas evenly as possible'by all the inking rollers of an inking mechanism. If only one singleform roller also applies the wetting liquid to the printing form, thequantity of ink delivered by it tothe printing plate is therebyobviously considerably reduced.

An object of the present invention is to eliminate these drawbacks ofprior art constnuctions.

Another object of the invention is toprovide a simple wetting mechanismat such a location of the train of rollers of the inking mechanism of anoffset printing machine, that the above-mentioned drawbacks are reducedto a minimum and, furthermore, that regulation of the quantity ofwetting medium supplied to the inking mechanism is readily possibleduring operation of the printing machine.

Other objects will become apparent in the course of the followingspecification.

These objectives were accomplished in the case of an offset printingmachine of the above-described type by a wetting mechanism having atrough for the wetting liquid, a scoop roller rotating therein, asqueezer roller rotating at regula-ble pressure against the scooproller, and a transfer roller disposed on the downstream side of thissqueezer roller and revolving at regulable pressure against the scooproller, the transfer roller bearing on a friction cylinder which isfirst when viewed in the direction of motion of the plate cylinders, andwhich drives the form rollers, or on an intermediate roller connectingthe first and second friction cylinders with each other, in either casewith sufficient pressure to ensure a friction drive effect.

For the printing of sheets or webs which are narrower than the length ofthe form rollers, the invention provides the arrangement of squeezerrollers and/0r streams of blown air between the squeezer roller and thetransfer roller, so as to prevent the supply of too much wetting liquidwhere it is not removed by the paper.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawings,showing by way of example, an embodiment of the invention in conjunctionwith an inking mechanism having three form rollers and two vibrator rollrunning in contact therewith.

In the drawings:

FIGURE 1 is a cross section taken along the line I-I of FIG. 2 through awetting mechanism according to the present invention, provided in anapproximately horizontal inking mechanism;

FIGURE 2 is a plan view of the inking mechanism according to FIG. 1;

FIGURE 3 is a cross section along the line III-III of FIG. 2, through aninking mechanism according to the invention, but in conjunction with anapproximately vertically disposed mechanism;

FIGURE 4 is a cross section along the line IVIV of FIG. 3, through awetting mechanism according to the invention, having a blower device.

With reference to FIG. 1 of the drawings, the purely diagrammaticallyindicated inking mechanism of the offset printing machine has a ductorroller 1 with a doctor blade 2, a vibrator 4 oscillating about a pivotpoint 3, and a steel cylinder 5 with associated rubber rollers 6 and 7.The roller 7 contacts a vibrator roll 8, with which rubber rollers 9 and10 are associated. The vibrator roll 8 contacts a rubber roller 11 whichis followed by a vibrator roll 12 and a form roller 13. The vibratorroll 12 communicates, through a rubber roller 14, with a vibrator roll15 adjacent to which are form rollers 16 and 17. The ink applicatorrollers 13, 16 and 17 contact the printing plate 19 which is stretchedover a plate cylinder 18. Also associated with the vibrator roll 15 aretwo rubber rollers 20, 21. All rollers and cylinders rotate in thedirection of the arrows shown in the drawings.

The wetting mechanism has side walls 22 between which, by means ofscrews 24, a trough 23 is fixed to hold the wetting liquid.

Rotatably mounted in the two side walls 22 is a preferably hollow andexternally chromium-plate scoop roller 25. A squeezer roller 26 and ashaft 27 with two squeezer rollers 28 are rotatably mounted in bearings29 which are adapted to slide in slots 30 in the side walls 22 so that,by means of wing screws 31 which are provided in plates 32 rigid on theside walls 22, they can be brought closer to the scoop roller 25 againstthe pressure of springs 33. Thus the squeezer roller 26 and/ or squeezerrollers 28 can press to a greater or lesser extent agaisnt the scooproller 25.

It is intended that the squeezer rollers 28 should further reduce thethicknes sof the film of wetting liquid on the surface of the scooproller 25 which is determined by the squeezer roller 26 when, as alreadystated, the paper which is to be printed does not remove the wettingliquid from the printing form or the offset sheet. Its length,therefore, depends upon the extent to which the paper to be printed isnarrower than the scoop roller or the form rollers 13, 16 and 17. If,when printing on narrower paper, the same quantity of wetting liquid isfed to the form rollers over their entire length, too much wettingliquid will accumulate at a location from which it is not removed. Atsuch places, then, there is the danger that the ink will emulsify.

According to the embodiment of the invention shown diagrammatically inFIG. 4, it is possible to provide a blower apparatus instead of thesqueezer rollers 28 or between the squeezer rollers 28 and the transferroller 42. The blower apparatus consists of a tube 46 disposed at acertain distance above the scoop roller 25 and attached to the sidewalls 22 of the damping mechanism; over both ends of the scoop roller25, nozzles 47 are provided in the tube; they are adapted to blow airobliquely towards the ends of the scoop roller. The nozzles 47 can beopened or closed by rotation of rings 48, in each of which there is ahole 49. A tap 50 makes it possible to adjust the quantity of blowingair which is supplied through a hose (not shown). The blower device canbe used instead of or in addition to the squeezer rollers 28.

The entire wetting mechanism is pivotally secured by two bolts 34 tointermediate walls 35 of the printing machine, in which rollers 6, 9,10, 14, and 21 are also rotatably mounted; it is pressed resiliently (ina manner not shown) against the cylinders 5, 8, 12 and 15. Theintermediate walls 35 are secured by bolts 36 to the side walls 45 ofthe machine in which the vibrator roll and other cylinders are alsorotatably mounted in a manner which need not be described in detail (seeFIG. 2).

Rigid on the side walls 22 of the wetting mechanism are arms 37 intowhich are screwed screws 38 having counter nuts 39. The screws 38 bracethe pivotable wetting mechanism on eccentric members 40 which are keyedupon a shaft 41 which is rotatably mounted in the side walls 45 of themachine. The shaft 41, in a manner not further illustrated, is locked bymeans of a lever or the like either in the working position shown inFIG. 1 or, in order to lower the wetting mechanism and disengage thescoop roller from the transfer roller 42, it is rotated throughapproximately 180. The transfer roller 42 is rotatably mounted ineccentric bearings 43 which are secured to intermediate Walls 35. Thusthe necessary pressure between the rollers 42 and 14 can be adjusted. Onthe other hand, this makes it possible for the transfer roller 42,together with the other rollers of the entire inking mechanism, to becleaned while the wetting mechanism is lowered. The desired pressurebetween the scoop roller 25 of the wetting mechanism and the transferroller 42 is adjusted by means of screws 38.

As indicated by arrows in FIG. 1 which denote the direction of rotation,the film of wetting liquid deposited on the upper side of the scooproller 25 and reduced to minimal thickness by the squeezer roller 26 andpossibly squeezer rollers 28 and/or blower nozzles 47, reaches therubber roller 14 via the transfer roller 42. From the rubber roller 14,the wetting liquid reaches the printing plate 19, partly via thevibrator roll 12 and the form roller 13 which is the first to touch theprinting plate, and partly via the vibrator roll 15 and the subsequentform rollers 16 and 17. An even distribution of wetting liquid over allthree form rollers 13, 16 and 17 can be achieved by an appropriateadjustment of pressure between the ink applicator rollers and thefriction cylinders which precede them.

The wetting mechanism and the inking mechanism in the arrangement shownin FIG. 3 include the same parts as described above, indicated by thesame reference numerals. Parts of secondary importance are omitted fromFIG. 3. However, there are the following dilferences between theconstruction shown in FIG. 3 and the previously described construction.

The transfer roller 42 of the wetting mechanism according to FIG. 3 isin direct contact with the vibrator roll 12. In accordance with thearrows indicating direction of rotation, which are the same as those inFIG. 1, the wetting liquid passes from the transfer roller 42 via thevibrator roll 12 partially to the rubber roller 14, partially to theform roller 13 and from this latter onto the printing plate 19. Thatpart of the wetting liquid which is taken by the rubber roller 14 passesover the friction cylinder 15 to the ink applicator rollers 17 and 16and [from these to the printing plate 19.

According to the space arrangements in the printing machine, it ispossible that either the arrangement of wetting mechanism according toFIG. 1 or that according to FIG. 3 may be more expedient. Botharrangements, in conjunction with the wetting mechanism described, oiferthe advantages of the present invention.

The lowering of the wetting mechanism by pivoting about the pin members34 is indicated only as an example. The contact between the scoop roller25 and the transfer roller 42 can be achieved in any other way, forexample, by a parallel displacement of the entire wetting mechanism orby pivoting of the transfer roller 42 about the central point of thefriction cylinder which it touches. These and other variations andmodifications are to be included within the scope of the presentinvention.

What is claimed is:

1. In an offset printing machine, in combination, a plate cylinderadapted to rotate in a specific direction, a printing plate extendingover said plate cylinder, three spaced form rollers engaging separateportions of said printing plate, two spaced vibrator rolls, saidvibrator rolls being so spaced from said said cylinder that in thecourse of the rotation of said plate cylinder in said specificdirection, a portion of the circumference of said plate cylinder firstpasses adjacent to one of said vibrator rolls and thareafter passesadjacent to the other one of said vibrator rolls, one of said vibratorrolls engaging two of said three form rollers, the other one of saidvibrator rolls engaging the third one of said three form rollers, and awetting mechanism comprising a trough for the wetting liquid, a scooproller rotatably mounted in said trough, spaced squeezer rollersengaging said scoop roller and rotatable therewith, means connected withsaid squeezer rollers for varying the pressure exerted by said squeezerrollers upon said scoop roller, a transfer roller located to one side ofall of said squeezer rollers and engaging said scoop roller, meansconnected with said trough for varying the pressure exerted by saidtransfer roller upon said scoop roller, and means including one rollerthat directly engages both of the said vibrator rolls for transmittingthe wetting liquid from said transfer roller to both vibrator rolls.

2. An offset printing machine in accordance with claim 1, wherein thelast-mentioned means comprise a rubber roller engaging the transferroller and both vibrator rolls.

3. An ofiset printing machine in accordance with claim 1, wherein thelast-mentioned means comprise a rubber roller engaging both vibratorrolls, the transfer roller engaging directly one of said vibrator rolls.

References Cited UNITED STATES PATENTS 1,566,800 12/1925 MacArthur118-63 2,322,533 6/1943 Mayer 11863 5 2,332,385 10/1943 Lauring 118-631,364,257 1/1921 Dobbertin 101-148 2,002,815 5/1935 Harrold 1011412,043,995 6/1936 Goedike 101148 XR 2,689,522 9/1954 Curtis 101148 XR 103,038,405 6/1962 Wojciechowski et al. 101-148 EDGAR S. BURR,

Primary Examiner.

U.S. Cl. X.R.

